Method and system for providing fuel to internal combustion engines

ABSTRACT

The present invention relates to a system and method for providing fuel to internal combustion engines including fuel activation prior to injection. The method carried out by the system comprises dissolving a mixture of gasses providing improved fuel dispersing after fuel injection into a combustion chamber. Dissolved gasses desorption is stimulated from a unsaturated fuel solution. Full control of fuel flows with dissolved gas/gasses to and from injectors and FET technology based on Henry&#39;s law (dissolving gasses in the liquids) and Kelvin principle (vapor pressure over droplet surface). The system consists of compact components, including exhaust gasses recirculation system which can be easily added to existing diesel and gasoline engine fuel supply systems. The method and system were tested with four different types of engines and provides fuel economy in 12-20% decrease of emissions and up to 25% at variable engine loads and significantly at engine cold start.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Divisional Application of Continuationapplication Ser. No. 13/920,508, filed Jun. 18, 2013, which is aContinuation of application Ser. No. 12/798,513, filed Apr. 6, 2010, nowU.S. Pat. No. 8,464,694, the entire disclosures of which areincorporated herein in their entireties.

FIELD OF INVENTION

The present invention relates to liquid fuel combustion and, moreparticularly, to the preparation of liquid fuels for combustion in acombustion chamber of internal combustion engines.

BACKGROUND OF THE INVENTION

In existing internal combustion engines such as diesel and gasolineengines, as well as other types of engines a fuel is injected into acombustion chamber at high pressure. A charge of the fuel is injected bymeans of solenoid injectors controlled by an on-board microcomputer andconnected to a common rail. The on-board microcomputer controlsinjection timing and duration as well as an injection pressure by meansof a two-stage main fuel pump. To provide better fuel atomization afterinjection into combustion chamber the fuel pressure in the common railupstream of the injectors is maintained at high level, e.g., in dieselengines the fuel pressure is maintained at 2000-2400 bars.

Currently different approaches are used to improve the fuel atomizationand dispersion in the combustion chamber after injection. For example,joint injection of hydrogen or natural gas with gasoline is used, inother systems a compressed air stream is directed to the fuel sprayinjected into the combustion chamber. There is also an approach wherefuel and air are induced with the same charge to reduce coalescence ofthe fuel microdroplets after the injection.

There are known attempts to disperse fuel by dissolving some gas, e.g.,air or carbon dioxide, in the liquid fuel and subsequently injectingthis solution into the combustion chamber. When injected into thecombustion chamber the dissolved gas is released from the solutionproviding very fine dispersion of the liquid fuel. In U.S. Pat. No.6,273,072 (Knapstein et al.) and U.S. Pat. No. 7,011,048 (Gurin et al.),there are described methods and devices for implementation andutilization of the abovementioned effect. The described systems requirespecial devices that are supposed to work within a certain range ofparameters and at the same time certain conditions should be observed toprovide the fuel/gas solution to the combustion chamber in propercondition. In practice it is difficult to satisfy both of theserequirements simultaneously, and the achieved effect is not stable atvarious loads.

SUMMARY OF THE INVENTION

An object of this invention is to provide a method and apparatus whichovercomes the abovementioned disadvantages and which provides forfurther improvement in the fuel injection into the combustion chamberthat reduces fuel consumption as well as emissions.

In accordance with invention there are provided technical solutions fordifferent types of fuel systems. The fuel is prepared for injection andcombustion in a special device, an absorber, where the fuel is contactedwith the gas or gasses. The gas pressure inside the absorber ismaintained higher than the fuel pressure supplied to the absorber; thegas is dissolved in the liquid fuel forming an unsaturated fuel solutionhaving no free gas phase. The resultant fuel solution is guided to amain fuel pump that further increases the pressure of the fuel solutionproviding no free gas phase. Upon injection in the combustion chamber inaddition to the hydrodynamic fuel atomization a violent degassing takesplace providing continuous chain breaking of fuel microdroplet to fine“nano” sizes. The combination of the gas desorption from the fuelsolution with the hydrodynamic breaking-up of the injected fuel providesa fundamentally new process of the fuel atomization in the combustionchamber. The fuel microdroplets continuously break up to significantlysmall sizes providing an extremely high interfacial curvature and liquidvapor (fuel) pressure increases by as much as 8-10 times. This effect isdescribed by the Kelvin equation and it is well known that the quickerliquid fuel evaporates the more rapid and effective the combustion ofthe gasoline or diesel is. One more important additional effect of thenew injection process: the continuous chain breaking of the fueldroplets caused by the gas desorption prevents coalescence of thedroplets and formation of a fuel film on the walls of the combustionchamber. As a result more fuel surface is available for contact withair. Thus the fuel burns faster and more completely giving less harmfulemissions.

Taking into account this and other objects a method of fuel activationand supplying into the combustion process is presented. The methodcomprises steps of:

a) Dissolving a gas/mix of gasses in fuel thereby transferring theliquid fuel into a state of unsaturated “fuel/gas” solution without anyfree gas phase; the fuel is dispersed in the absorber to increase thecontact surface with the gas supplied to the absorber at high pressureof up to 100 bar; the process is performed, preferably, at lowertemperatures, and gas used for dissolution can be a mixture of, forexample, exhaust gases and oxygen enriched air having O₂ content of upto 35% and fuel/mixture of gases ratio by weight of 1:0.055. The purposeof using the mixture with increased oxygen content is to increase thelocal concentration of the oxidant during gas desorption. The presenceof locally available oxidant helps more quicker fuel ignition.

b) Activating “fuel/gas” solution by changing the state of the“fuel/gas” solution for a short period of time to a boundary state ofoversaturated solution in such way as to minimize or exclude free gasbubbles flashing out of the fuel solution flow at the inlet of the mainfuel pump by lowing the pressure of the fuel solution flow or byultrasound treatment in a hermetic vessel comprising a vibrating elementthat by ultrafast oscillations forms partial pressure decrease of thefuel solution flowing through the vessel.

c) Merging the recirculation fuel solution flows pumped out after theinjection from common rail and main fuel pump, cooling down the fuelsolution to 50° C. and guiding it to the absorber to separate freegas/fuel vapor phase.

d) In the fuel system with single stage main fuel pump and distributedinjection pumps the return flow is cooled, separated from free gas/fuelvapor phase and guided to the inlet of the main fuel pump. Some fuelafter the main fuel pump is guided to a nozzle of a jet pump which isused to pump out free gas/fuel vapor phase from a gas separator and themix flow then is fed to the absorber to separated liquid and gas phases.This helps to avoid gas or vapor bubbles appearing that may createpressure pulses at the outlet of the main fuel pump and affect theoperation of the fuel injectors.

e) Preparing the gas mixture to be used for dissolution in the fuel bycooling and compressing the exhaust gases and mixing it with oxygenenriched air formed by filtering compressed air through a specialmembrane filter; prepared gas mixture is guided to the absorber fordissolving in the liquid fuel.

With this and other objects in view there is provided, in accordancewith the invention, a system for liquid fuel activation and feedingactivated liquid fuel to the combustion chamber for combustion,comprising:

a) an absorber for fuel conditioning, having a liquid inlet port forproviding a fresh liquid fuel from a fuel tank, a gas inlet port forproviding gas or gas mixture, an inlet port for providing returned fuelflows from an engine common rail and main fuel pump, and an outlet portfor supplying a fuel solution from the absorber to an engine;

b) a fuel solution activator for momentary transferring the fuelsolution to a state of oversaturated solution thereby preparing the fuelsolution to a burst gas desorption at injection into the combustionchamber;

c) a fuel supply subsystem for supplying the fresh liquid fuel to theabsorber with maintaining fuel level inside the absorber between min andmax limits;

d) a subsystem for collecting returned flows from the engine and mainfuel pump, separating free gas/fuel vapor, cooling down to 50° C. andguiding the returned flows to the inlet port of the main fuel pump;

e) a control system for controlling the fuel supply and engineoperation.

The system and method of operation of the invention with additionalobjects and advantages thereof will be best understood from thefollowing description of specific embodiments when read in connectionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows one of the embodiments of the invention for internalcombustion engines having common rail injection system.

FIG. 2 shows another embodiment of the invention for internal combustionengines having common rail injection system.

FIG. 3 shows an embodiment of the invention for diesel engines havingfuel supply system with fuel distribution pump.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 of the drawing shows one of the possible embodiments of thesystem for an internal combustion engine having common rail injectionsystem. The internal combustion engine can be a standard diesel orgasoline engine. The engine comprises a common rail injection system 1,a two-stage main fuel pump 2, a fuel tank 3, a primary fuel filter 4, afine fuel filter 5. The common rail injection subsystem comprises unitinjectors (not shown) for injecting fuel charge into a cylindercombustion chambers and fluidically connected with the outlet ports ofthe common rail.

The activation system according to the present invention consists of twosubsystems: a conditioning subsystem and a gas preparation subsystem.

The conditioning subsystem comprises an absorber 10, a feeding pump 11,a differential pressure regulator 12, a jet pump 15. Three-way valves 14and 16 are used to change from standard (base) fuel supply system to theconditioning subsystem and vice versa. Check valves 18, 19 prevent fuelto flow in wrong direction.

The gas preparation subsystem comprises a reactor 13 and two air andexhaust gases supply lines. Air from air source 26 flows through afilter 28, a compressor 29, a pressure regulator 30, and an oxygenenrichment membrane filter 31, a check valve 27 prevents air to flow inwrong direction; exhaust gases from exhaust line of the engine 20 flowsthrough a filter 22, a cooler 23, a compressor 24 and a pressureregulator 25, check valve 21 prevents exhaust gasses to flow in wrongdirection.

The gas mixture is prepared in the reactor 13 by mixing the exhaustgases as sources of CO₂ with oxygen enriched air that is formed afterambient air passes through the oxygen enrichment membrane filter 31.Mixing of two gas streams in equal portions by weight is provided bypressure regulators 25 and 30 having common control line. Requiredpressure of the gas mixture is provided by compressors 24 and 29 andcontrolled by the pressure regulators 25 and 30.

The fuel from fuel tank 3 is delivered by feeding pump 11 to the nozzlesmounted in the absorber 10. The feeding pump 11 provides the fuelpressure P₁. The gas mixture from the reactor 13 is guided to the gasinlet port of the absorber 10 under gas pressure P₂ which is controlledby pressure regulator 17. Pressure regulator 32 maintains the gaspressure inside the absorber 10 at set level P₂. The gas pressure P₂ isset lower than the fuel pressure P₁ providing satisfactory workingcondition for the fuel dispersing by the nozzle in absorber 10. Thedispersing of fuel in gas results in achieving a significant amount ofgas being dissolved in fuel. An outlet port located at the bottom of theabsorber 10 is fluidically connected to the inlet port of the main fuelpump 2. The differential pressure regulator 12 positioned in theconnection line between the absorber 10 and main fuel pump 2 temporarilyreduces the fuel solution pressure. The reduced pressure transfers thefuel solution into the boundary state of saturated solution thusfacilitating the gas desorption from the fuel by destroying sorptionlinks between liquid and gas molecules. This step improves effectivenessof the desorption process at injection and improves the atomization ofthe injected fuel charge. In addition the differential pressureregulator 12 compensates for pressure spikes arising during the absorber10 operation. Instead of differential regulator 12 an ultrasonicmagnetostrictive actuator in a hermetical vessel through which a liquidfuel/gas solution flows can be used. Main fuel pump 2 again increasesthe pressure of the fuel solution as much as 2 times and returns thefuel solution in the state of unsaturated solution. In such state themain fuel pump 2 delivers the fuel solution to the common rail 1 andunit injectors (not shown) for combustion.

It is well known that the gas solubility in liquid is proportional tothe partial pressure of the gas over the liquid surface and theconcentration of the gas dissolved in liquid is in inverse proportion tothe liquid temperature. As the fuel solution parameters in supply lineare maintained higher than parameters in the combustion chamber atinjection in addition to hydrodynamic breaking of fuel stream byinjector the gas dissolved in the fuel solution violently escapes fromthe liquid thus providing additional atomization of the fuel to morefinest aerosol as well as even distribution over the volume of thecombustion chamber. The faster evaporation on superfine fuelmicrodroplets at high temperature present in the combustion chamberprovides speedy propagation of the flame front. This way faster and moreefficiently burnt fuel delivers more energy at optimal piston andcrankshaft position. As a result it takes less fuel to produce the sameamount of power, as well as provides a reduction of emissions.

Since the main fuel pump 2 delivers more fuel than the internalcombustion engine can consume to produce useful power recirculationlines are provided for returning excess fuel. Recirculation fuelsolution flows from common rail is cooled down to 50° C. in cooler 6 andthen merged with 1 first stage of the main fuel pump 2 in the jet pump15: Recirculation fuel solution from the common rail having higherpressure is guided to the nozzle of the jet pump 15; the ejected flowcreates low pressure in the mixing chamber and recirculation flow fromfirst stage of the main fuel pump 2 is sucked into the mixing chamber ofthe jet pump thus providing lower pressure at the drainage port of themain fuel pump and better conditions for gas separation.

Three-way valves 14 and 16 are used to switch between conditioned modeand base mode of engine operation. In conditioned mode operation themixed recirculation fuel solution flow from jet pump 15 is guided to therecirculation inlet of the absorber. In base mode both valve are set toinitial position and recirculation flow from jet pump is guided to thefuel tank 3.

In another embodiment (FIG. 2) a gas separator can be provided inrecirculation line for removing free gas/fuel vapor phase fromrecirculation fuel solution flow. The recirculation flow is cooled,preferably, to 50° C. in a cooler 6 and is then guided to the gasseparator 7. The liquid fuel solution from gas separator is fed to theinlet of main fuel pump 2 and separated free gas/fuel vapor is guided tothe gas port of the absorber 10 using a low pressure compressor 8.

FIG. 3 shows a preferred embodiment for an internal combustion enginehaving one-stage main fuel pump 2 and distributed unit injectors 1. Inconditioned mode operation the recirculation flow from unit injectors 1contains high concentration of dissolved gasses so it is guided back tothe inlet of the main fuel pump. But passing through a cylinder head itcontains some free gas/fuel vapor that should be separated from therecirculation flow as it may damage the unit injectors. Therecirculation flow is cooled preferably to 50° C. in a cooler 18 andfree gas/fuel vapor is separated in a gas separator 19. A jet pump 15 isused to remove separated free gas/fuel vapor from the gas separator 19.To provide operation of the jet pump 15 some fuel after the main fuelpump 2 is guided to the nozzle of the jet pump 15 and the low pressurecreated by the ejected flow sucks the separated free gas/fuel vapor. Themixed flow from the jet pump is guided to the absorber 10. To keep thepressure at the inlet of unit injectors 1 at required level the pressureregulator 36 is used.

To shut the engine off or at idle operation the fuel supply should beswitched to the base mode using three-way valves 14 and 16 and shuttingout the fuel supply to the absorber 10.

Before parking the vehicle for a long period of time the cylinder headand the fuel supply should be flushed from conditioned fuel by operatingthe engine on the base unconditioned fuel for about 30-90 seconds.

The present invention is not to be construed as limited to the formsshown which are to be considered illustrative rather than restrictive.

1. A method for providing liquid fuel to internal combustion enginesincluding additional steps of a fuel activation prior to injection andcombustion in a combustion chamber; the steps comprising: (a) dissolvinga gas/gasses in the fuel thus transfer the liquid fuel flow into a stateof unsaturated fuel solution without any free gas phase; providing the“liquid fuel/gas” solution to a main fuel pump, and (b) changing thestate of the abovementioned “liquid fuel/gas” solution to a boundarystate of oversaturated solution in such way as to minimize free gasbubbles flashing out of the fuel solution flow at the inlet of the mainfuel pump.
 2. A method for providing fuel to internal combustion enginesaccording to claim 1, wherein the step of gas dissolving in the liquidfuel flow and transferring liquid fuel to the “fuel/gas” unsaturatedsolution is performed at high gas pressure, and highly developed contactsurface between liquid and gaseous phases, and, preferably, at lowertemperatures.
 3. A method for providing fuel to internal combustionengines according to claim 1, wherein the first step of liquid fuelactivation—transfer to the state of “fuel/gas” unsaturated solution—isperformed in a special device, an absorber, with feeding it with liquidfuel and a mixture of gasses such as exhaust gasses and oxygen-enrichedair having partial pressure of oxygen up to 35%, and “fuel/gasses” ratioby weight of, preferably, 1:0.055, based on carbon dioxide andoxygen-enriched air content, and gas mixture pressure up to 100 bar. 4.A method for providing fuel to internal combustion engines according toclaim 3, wherein at the second step of the fuel flow activation thestate of “fuel/gas” fuel solution is changed for a short period of timeto the boundary state of oversaturated solution, preferably, before thefuel solution enters an inlet port of the first-stage of the main fuelpump, e.g., by decreasing liquid fuel flow pressure.
 5. A method forproviding fuel to internal combustion engines according to claim 4,wherein the step of changing the state of “fuel/gas” fuel solution tothe boundary state of oversaturated solution before the main fuel pumpis performed by a high-frequency ultrasound treatment of the fuelsolution flow in a hermetical vessel that comprises a special vibratingelement having high-frequency oscillations and forming local pressurereliefs thus destroying at least partially sorption links between liquidfuel and gas molecules.
 6. A method for providing fuel to internalcombustion engines according to claim 4, wherein return lines areprovided to recycle unused fuel from the main fuel pump and common railafter injection; both return flows are merged, and common return flow isguided for separating free gas phase and fuel vapour phase from theliquid fuel flow; the liquid fuel flow is then cooled down, preferably,below 50° C. and guided to the “fuel/gas” oversaturated fuel solutionsupply line connected to the inlet port of the main fuel pump.
 7. Amethod for providing fuel to internal combustion lines having fueldistribution pump according to claim 6, wherein the separated gaseousand vapour flow is guided from the fuel separator to the absorber usinga liquid jet pump. The return fuel solution flow from the mail fuel pumpis guided to the jet pump nozzle.
 8. A method for providing fuel tointernal combustion engines according to claim 6, wherein a jet pump isprovided for merging and guiding the return flows to the absorber; thereturn flow under high pressure from the common rail is guided to anozzle of the jet pump whereas the return flow with lower pressure afterthe first stage of the main fuel pump is sucked in a mixing chamber ofthe jet pump thus increasing the pressure for supplying the merged fuelsolution flow to the absorber and decreasing the backpressure to removedrainage before the second stage of the main fuel pump.
 9. A method forproviding fuel to internal combustion engines according to claim 3,wherein the gaseous mixture is formed in a hermetical vessel bycompressing and cooling the exhaust gases and simultaneously compressingthe air and guided it to a membrane filter providing the oxygen enrichedair; the pressure of the gasses inside the vessel is maintained by apressure sensor having two set pressure limits: when the pressuredecreases to a lower pressure limit the compressors are switched on, andwhen the pressure raises to an upper pressure limit the compressors areswitched off; differential pressure regulators for both gas flows havecommon control base line providing optimal supply and mixing of gaseouscomponents.